14. The Action 



of 

 Chemical Agents 



i 



.nhibition by chemical agents has probably been the 

 single most active field of investigation of the fungi. Of necessity, 

 however, much of this work has been directed to the practical prob- 

 lem of controlling the fungi pathogenic to plants and to man and 

 other animals and the fungi that destroy economically valuable com- 

 modities. Theoretical problems have, of course, not been neglected; 

 the important work has been summarized by Martin (278) and more 

 recently by Horsfall (172, 174). 



In a study of the physiology of fungi, such as this, it seems appropri- 

 ate to concentrate attention upon those materials, regardless of their 

 practical importance, about which we have some information as to 

 mode of action. This approach neglects many fascinating problems in 

 the chemical inhibition of fungi: the role of antibiotic substances in soil 

 (152, 425) and the use of purified antibiotics (218, 337, 396, 430), the 

 expanding field of chemotherapy of plants (90, 175, 176, 402), and many 

 of the developments in the use of organic compounds as fungistatic or 

 fungicidal agents. It is to be hoped that sufficient attention will be 

 devoted to mode of action so that these topics can be treated theoret- 

 ically in the near future. 



The chapter has been organized so as first to consider some general 

 problems and then to give detailed attention to a few types of com- 

 pounds — heavy metals, sulfur, quinones, and the chelating agents — 

 which have been most actively investigated. 



440 



